In general, a transmission is a device for accelerating or decelerating a motive power.
Such a transmission is coupled to a motor driving shaft to thereby automatically or manually change the speed of the motor power. In case of the manual transmission, a clutch is located between the motive power and the transmission to thereby achieve a speed change in a state where the motive power to the transmission is interrupted. In addition, the automatic transmission does not have a restraining means, such as the clutch, and automatically changes the speed according to a pressure change or the like of an output side.
However, the manual transmission according to a prior art has a problem in that it is inconvenient in use and it becomes bulky since the manual transmission essentially requires the clutch. In addition, the automatic transmission also encounters a problem in that it becomes bulky and it is frequently out of order since the automatic transmission itself is complicated in structure.